1. Field of the Invention
The present invention relates to a communication system. More particularly, the present invention relates to a system controlling communication among multiple industrial control systems.
2. Description of Related Art
Industrial control systems (ICS) for management and control on industrial and infrastructure systems are known (for example, see “SCADA”, [online], Wikipedia, [searched on Mar. 30, 2011], the Internet <URL: http://www.wikipedia.org/wiki/SCADA>). Conventionally, a number of industrial control systems operate within their own specific protocols without being connected to an external network.
Recently, however, a general communication protocol such as the Internet protocol has been used to connect industrial control systems, and the number of such systems connected to both an intra-company system and an external network is increasing. If maliciously attacked from the outside, such industrial control systems are required to take actions to prevent the attacker from taking control over control-target equipment, where such actions can include immediate shut down of the control-target equipment.
There can be a case, however, where an industrial control system cannot shut down a control target in a short time, depending on the type of the control target, due to a technical factor or from a viewpoint of a social demand. Therefore, industrial control systems are required to take appropriate actions for each control target upon detection of anomaly due to an outside malicious attack.